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Testosterone Total, and Free Testosterone

March 25, 2023Chemical pathologyLab Tests

Table of Contents

  • Testosterone
      • Sample for Testosterone
      • Precautions for Testosterone estimation
        • Purpose of the test (Indications) for Testosterone level
      • Pathophysiology of Testosterone
      • Testosterone secretion: 
      • The pituitary gland role in testosterone:
      • Testosterone functions:
      • Testosterone metabolism:
      • NORMAL Testosterone
        • Testosterone Free
        • Testosterone Total (blood)
          • Source 2
        • Total testosterone
        • Total testosterone
      • Increased values of Total Testosterone are seen in the following:
      • Decreased Total testosterone value is seen  in Males:
        • Increased Free Testosterone is seen in Females:
        • Decreased Free Testosterone is seen in Males:
      • Questions and answers:

Testosterone

Sample for Testosterone

  1. It is done in the serum.
  2. Can use heparinized plasma.
  3. 24 hours of the urine sample.
  4. Separate the serum immediately; if kept for a longer period (more than 6 hours),  may get false high values.
  5. The sample is stable at 1 to 4 °C for one week.
  6. Free Testosterone is stable for 1 to 2 days at 4 °C.
  7. At -20 °C sample is stable for 6 months.

Precautions for Testosterone estimation

  1. Separate serum from the cells within 6 hours; otherwise, there is a false value elevation.
  2. The level is high in adults in the AM sample and 25% lower in the evening sample.
  3. In females, lower values increase 1 to 2 days mid-cycle.
  4. High values after the exercise.
  5. Value is decreased after the overload with glucose.
  6. There is a slow progressive decrease after the age of 50 years.

Purpose of the test (Indications) for Testosterone level

  1. In males, this test is done to evaluate the following:
    1. Hypogonadism.
      1. This stimulation can be done by giving clomiphene and HCG.
    2. Cryptorchidism.
    3. Impotence.
    4. Pituitary gonadotropic function.
    5. Infertility.
    6. Precocious puberty.
    7. Tumor marker for the testicular tumors.
  2. In the female, this test is done to assess:
    1. Hirsutism and virilizing syndrome.
    2. Ambiguous sex character.
    3. Precocious puberty.
    4. Tumor marker for ovarian tumors.
    5. Maybe part of the fertility workup of the chronic anovulatory cycle due to the polycystic ovary.

Pathophysiology of Testosterone

  1. Testosterone is the main androgen secreted by the testes, and its production increases by puberty.
    1. Women only produce 5% to 10% of the testosterone as much as males.
  2. Androgenic hormone includes:
    1. Dehydroepiandrosterone (DHEA).
    2. Androsterone.
    3. Testosterone.
  3. The adrenal gland produces   DHEA, Cortisol, Aldosterone, and Testosterone.
Adrenal androgens

Adrenal androgens

  1. Testes produce DHEA.
  2. Ovaries produce DHEA.
  3. DHEA is a precursor of the Androstenedione precursor of Testosterone and estrogen.
Testosterone synthesis

Testosterone synthesis

  1. Testosterone is responsible for the development of male secondary characters.

Testosterone secretion: 

  1. In men, testosterone is secreted by:
    1. Adrenal glands produce 2/3 of the total testosterone.
    2. Testes produce 1/3 of the total testosterone.
  2. In females, testosterone is secreted by:
    1. The adrenal gland is the source of all testosterone in females.
    2. Ovaries also produce some testosterone.
Testosterone source in the female

Testosterone source in the female

  1. Testosterone fluctuation in the level.:
    1. In the male, there is a peak level early in the morning.
    2. The female has cyclic elevation for 1 to 2 days around mid-cycle.
  2. Testosterone is made by:
    1. In males, mainly by the Leydig cells, which is almost 95 % of the total.
    1. In female :
      1. About 50 % is made by converting DHEA into fatty tissue.
      2. 30% conversion of DHEA in the adrenal glands.
      3. 20% is made directly by the ovaries.

The pituitary gland role in testosterone:

  1. The pituitary gland produces LH in males and FSH in females.
  2. LH  stimulates the Leydig cells to produce  Testosterone.
  3. FSH  Stimulates Sertoli cell to help in spermatogenesis.
Testosterone synthesis in the testes

Testosterone synthesis in the testes

Testosterone functions:

  1. Testosterone stimulates spermatogenesis and secondary sex character.
  2. Testosterone Increased production is seen in:
    1. In Male produces premature puberty.
    2. In Females produce masculinity (manifested by amenorrhea and excessive growth of body hairs).
  3. Testosterone exists in two forms in the serum:
  4. In males:
    1. Circulating testosterone is bound to:
      1. 60% to 65% strongly bound to sex hormone-binding globulin (beta-globulin).
      2. 20% to 40% is bound to serum albumin.
      3. 1% to 2% testosterone is free or unbound testosterone. This is the only biologically active testosterone.
  5. In females:
    1. Abound fraction consists of:
      1. 1% is free testosterone.
      2. 80% bound to sex hormone-binding globulin (SHBD).
      3. 19% bound to albumin.
    2. The free fraction is 2% unbound to the sex hormone globulin and albumin.
  6. Total testosterone = Bound fraction + Free fraction.
    1. Free fraction is the Active form.
Testosterone formation and functions

Testosterone formation and functions

Testosterone metabolism:

  1. Testosterone is metabolized in the liver, and the main metabolites are:
    1. Androsterone.
    2. DHT (dihydrotestosterone).
    3. These are further metabolized into androstenedione and etiocholanelone.
    4. End metabolites are excreted through the kidneys.
  2. The main metabolites of adrenal, testicular, and ovarian hormones are secreted through the kidneys as 17-ketosteroids.
Testosterone and role of anterior pituitary gland

Testosterone and the role of the anterior pituitary gland

NORMAL Testosterone

Source 1

Testosterone Free

Age pg/mL
Male Female
Cord 5 to 22 4 to 16
Newborn (1 to 15 days) 1.5 to 31.0 0.5 to 2.5
1 to 3 month 3.3 to 8.0 0.1 to 1.3
3 to5 month 0.7 to 14.0 0.3 to 1.1
5 to 7 month 0.4 to 4.8 0.2 to 0.6
Children
6 to 9 year 0.1 to 3.2 0.1 to 0.9
10 to 11 year 0.6 to 5.7 1.0 to 5.2
12 to 14 year 1.4 to 156 1.0 to 5.2
15 to 17 year 80 to 159 1.0 to 5.2
Adult 50 to 110 1.0 to 8.5
  • To convert into SI units x 3.47 = pmol/L

Testosterone Total (blood)

Age ng/dL
Male Female
Cord 13 to 55 5 to 45
Premature 37 to 198 5 to 22
Newborn 75 to 400 20 to 64
1 to 5 month 1 to 177 1 to 5
6 to 11 month 2 to 7 2 to 5
Children
1 to 5 year 2 to 25 2 to 10
6 to 9 year 3 to 30 2 to 20
Puberty Tanner stage
1 2 to 23 2 to 10
2 5 to 70 5 to 30
3 15 to 280 10 to 30
4 105 to545 15 to 40
5 265 to 800 10 to 40
Adult 280 to 1100 15 to 70
Pregnancy 3 to 4 x adult level
Postmenopausal 8 to 35
  1. To convert into SI unit x 0.0347 = nmol/L

Urine

  • 20 to 50 years
  • Male   = 50 to 135 µg/day
  • Female = 2 to 12 µg/day
    • >50 years
      • Male = 40 to 60 µg/day
      • Female = 2 to 8 µg/day
Source 2

Total testosterone

  • Men = 3 to 10 ng/mL
  • Women = <1 ng/mL
  • Prepubertal boys and girls = 0.05 to 0.2 ng/mL

Source 4

Free testosterone

  • Men = 50 to 210 pg/mL.
  • Women = 1.0 to 8.5 pg/mL.
  • Children:
    • Boy = 0.1 to 3.2 pg/mL.
    • Children Girl = 0.1 to 0.9 pg/mL.
  • Puberty:
    • Boy = 1.4 to 156 pg/mL.
    • Puberty Girls = 1.0 to 5.2 pg/ml.

Total testosterone

  • Men = 270 to 1070 ng/dL.
  • Women = 15 to 70 ng/dL.
  • Postmenopausal women = 8 to 35 ng/dL.
  • Pregnant women = 3 to 4 ng/dL

Testosterone by age

  1. Serum level of testosterone :
  2. In male infants :
    1. By 2 weeks = around 25 ng/dL.
    2. BY 2 months = around 275 ng/dL.
  3. In female infants :
    1. By 2 weeks = around 25 ng/dL.
    2. By 2 months = Value decreases and remains low throughout early childhood.

Increased values of Total Testosterone are seen in the following:

  1. Male
    1. hyperthyroidism.
    2. Adrenal tumors.
    3. Adrenal Hyperplasia.
    4. Hypothalamic tumor, Pinealoma.
    5. Viral encephalitis.
    6. Testicular or extragonadal tumors where Leydig cells produce testosterone.
    7. Testosterone resistance syndrome.
  2. Female
    1. Adrenal neoplasm.
    2. Hilar cell tumor.
    3. Idiopathic Hirsutism.
    4. Trophoblastic disease during pregnancy
    5. Ovarian tumors
    6. Polycystic ovary.

Decreased Total testosterone value is seen  in Males:

  1. Klinefelter syndrome.
  2. Pituitary failure leading to hypogonadism.
  3. Hypopituitarism may be primary or secondary.
  4. Orchiectomy.
  5. Delayed puberty.
  6. Down syndrome (trisomy 21).
  7. Cirrhosis.
  8. Cryptorchidism due to undescended testes.

Increased Free Testosterone is seen in Females:

  1. Hirsutism.
  2. Virilization.
  3. Polycystic ovaries.

Decreased Free Testosterone is seen in Males:

  1. Hypogonadism.
  2. Old age.

Questions and answers:

Question 1: What type of cell is the source of testosterone?
Show answer
Leydig cells produce testosterone under the influence of LH hormone.
Question 2: Total testosterone is biologically active?
Show answer
No, only free testosterone is biologically active.

Possible References Used
Go Back to Chemical pathology

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